1. Field of the Invention
The present invention relates to image processing for binarizing image data upon detection of a specified pattern.
2. Description of the Related Art
In recent years, with the developments of functions and performances of color copiers, it becomes possible to obtain a color copy with high quality even by using a commercial scanner, a computer, a color printer and the like. Therefore, it is necessary to provide an effective method for preventing the subsequent counterfeiting acts for paper money, and the like. One of the counterfeiting prevention methods is a technique for inhibiting the generation of an image resembling closely a paper money and the like, upon detection of a specified pattern at the time of copying.
However, an input image is a color image having a great amount of data, and it takes a long time to carry out the corresponding process on the image. From the practical point of view, the process needs to be performed at a high speed, with the result that the processing circuit becomes bulky, complex, and expensive. Moreover, since color hues of the image tend to change depending on scanning conditions, detection of a specified pattern using color discrimination requires a high-performance processing circuit, that is, an expensive circuit.